Dynamically vertical centralisation

I have a table structure that I am using to display a timetable and list of duties for a small project at work. The left column has a list of people that will be assigned to tasks, and the top row is the day of the week. The individual cells between contain the actual task - a 3 or 4 letter code.

I have managed to vertically centralised the cells by padding top and bottom to force the text into a set position. However, The names column often goes over the length of the line and wraps underneath, meaning that I need to dynamically centralise that column.

I have tried margin-top:auto and margin-bottom:auto but that has no effect. The text is still flush to the top of the "box".
As everything is floated left, any difference in the size of the box will cause the entire table to skew.

The names and duties are pulled from a SQL database and it is all put together in sequence, line by line.

Below are the stylesheet codes that I am using, with annotations to show what they are used for.

-- Main wrapper for the page -- This is working
#plwrap{width:770px;
font-size:14px;
margin-left:auto;
margin-right:auto;}